Lift truck mast and ram assembly



United States Patent [mentor Bronislous I. Uimki [72] 2.788.148 4 1957Parcell 92146X Pa|mB3h,Fl0rld8 2,221.3]6 l 1958 Saints 9ll67X '[211AppLNo. 817,218 3339.400 6 1962 Trent. 92,161 {22] Filed March v h3,042,149 7.1962 Comfort 9252K A diigsinnnfse r. No. 665,826,5 p -6,1967, 3,049,334 8/1962 Montague 251 367X now atent N0.3,485,323,Whih is3,128,468 4/1964 Bade 92 161 continuation-impart ofSer. No. 601,638,3,172,339 3,1965 Quayle. 92 5 Dec. 14,1966, now abandoned. 3212,6 1 101965 Garnett H 212/55 [45] Patented 061. 20, 1970 FOREIGN PATENTS i731Awgn g g 418,560 231967 Switzerland a. 12 /17 Prl'muqv xaminer Martin P.Schwadron Assistant xaminerl.eslie Jv Pa ne [54] LIFT TRL'CK MAST ANDRAM ASSEMBLY Almrne Teagno and Todd 9 Claims, 8 Drawing Figs. 152} Cl H92/146,

. 92/]6492/165 187/9 187/17 ABSTRACT: A mast construction for a lifttruck in which l5l Int. (J FUlb 1/00, each i h aswmbly is moved by a ramsupported on a bts I 36Gb 9/20, B6613 1,1104 plate and acting against athrust plate of an adjacent upright 1 1 Fleld 593mb 92/ 161 assembly.The rams are connected in series through a hydraul6 f 14551152, 53;91/169, 167; I lie circuit including therespectixe base and thrustplates and 7 l 2/ by l rigid piping extending from the base plate to thethrust plate of I each upright assembly Further, the particularconstruction of i References voted the upright assemblies and theposition of the rams provides L IT STATES PATE5T5 an extremely compactcombination protecting the rams from 2,651 ,180 9/1953 Haller 92/ 1 46Xlateral bending forces applied to the mast.

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LIFT TRUCK MAST AND RAM ASSEMBLY This application is a Division of myearlier application Ser. No. 665,826, filed Sept, 6, 1967, for LiftTruck Mast and Ram Assembly now U.S. Pat. No. 3,485,323, issued Dec. 23,1969, which is a ContinuationIn-Part of application Ser. No. 601,638filed Dec. 14, 1966 and now abandoned.

This invention relates to the assembly of a ram relatively to an uprightassembly or load lifting mast. More particularly, my invention relatesto means for assembling either one end of a hydraulic ram to an upright,or the opposed ends of a rum to two telescoping uprights, whereby theextension of the ram will lift either a second upright relatively to afirst upright, or will lift a load carriage relatively to an upright.

As those skilled in the art well appreciate, it is extremely importantto utilize a minimum of hose or piping for bringing fluid to a hydraulicram. This is due to the fact that the fluid pressures used in industrialtrucks are extremely high so that the longer the hose or other passagethrough which the fluid moves, the greater the risk of breakage and lossof fluid. Further, industrial trucks must be extremely compact and it ishighly desirable, therefore, to limit the amount of hose or piperequired, and the resulting hydraulic friction.

Those skilled in the art are also fully aware of the fact that while itis desirable to obtain maximum throw or extension of a hydraulic ram,this maximum extension should be obtained through a ram having a minimumoverall length. As a matter of interest, inventors have been attemptingfor many years to achieve maximum extension with minimum length of ram.

My invention contributes a ram for a mast having an extremely long throwin proportion to its overall length, all because of the manner in whichit is assembled to one upright or to a pair of telescoping uprights inwhich one upright slides on another upright.

As a further feature of my invention, I contribute a mast assemblyutilizing one ram for each movable upright of an extremely compactconstruction highly resistant to lateral bending forces applied to themast, and thus prevents such forces from effecting the operation of therams.

It is a further feature of my invention that through the ram mountingmeans I have conceived, it is possible to have a minimum of piping forthe hydraulic fluid, with the further feature that none of this pipingneed be flexible, thereby making possible the use of rigid piping.

As still a further feature of my invention, I contribute a mast assemblyutilizing more than one ram, in which all of the rams may be identicalin construction and in which all of the mounting means for securing therams in position may be identical.

As a particular feature of my invention, the ram thereof is formed withan open end adapted to fit against an open surface on the base platethat supports the ram. Actually, the open end of the ram is adapted tofit into a bore in the plate that supports it and to receive fluid frompassage means carried by the plate and preferably internal of the plate.

Where the fluid is adapted to flow from one ram toward a second ram forsequential operation of the rams, that end of the ram opposite thesupport plate and operating against the thrust plate of the nextupright, may have the same construction as that just described.Therefore, the thrust plate may be constructed as is the base plate withthe relatively moving portion of the ram assembled thereto as is therelatively stationary portion assembled to the base plate.

Where a series of uprights are to be utilized, I am able to secure aseries of rams for lifting the series of uprights. Each uprightfunctioning in the assembly will have, where necessary, a base plate anda thrust plate, and preferably the base plates and thrust plates willhave the same construction although that is not essential. Therelatively movable portions of the ram, which are a cylinder and apiston, may be applied between the thrust plate and the base plate.Then, through suitable means such as will be described hereinafter, andwhich preferably take the form ofa hollow nut, the piston and cylindermay be secured to the thrust and base plates. Where the piston issecured to the thrust plate, it will supply fluid to the passage in thethrust plate, this fluid then moving through a rigid pipe downwardly tothe base plate of the secondary upright and to a second ram, and so onas may be desired.

l have thus outlined rather broadly the more important features of myinvention in order that the detailed description thereof that followsmay be better understood. There are, of course, additional features ofmy invention that will be described hereinafter and which will form thesubject of the claims appended hereto. Those skilled in the art willappreciate that the concept on which my disclosure is based may readilybe utilized as a basis for the design of other structures for carryingout the several purposes of my invention. It is important, therefore,that the claims be regarded as including such equivalent constructionsas do not depart from the spirit and scope of my invention in order toprevent the appropriation of my invention by those skilled in the art.

In the drawings:

FIG. I is a vertical side elevational view showing schematically thearrangement of my fork lift truck to which the mast assembly of thepresent invention is applied.

FIG. 2 is a plan view of FIG. 1.

FIG. 3 is a vertical side elevational view showing the truck of FIG. Iin a full lift position.

FIG. 4 is a cross-sectional view through the mast taken along the lines4-4 of FIG. 1.

FIG. 5 is a cross-sectional view similar to FIG. 4 but taken along thelines 5-5 of FIG. 1.

FIG. 6 is an enlarged fragmentary sectional view showing the lower endof the upright assembly and ram.

FIG. 7. is an enlarged fragmentary sectional view showing the upper endofthe upright assembly and ram.

FIG. 8 is an enlarged elevational view partly in section and partly inparts broken away showing the hydraulic rams for each of the uprightsand the hydraulic circuitry for supplying power to each of the rams.

Referring to the drawings and more particularly to FIG. 1, a fork lifttruck 10 comprises a main frame 11 having rear wheels 12 and frontwheels 13 controlled by means of steering wheel 14. A suitable powerplant is enclosed within the housing 15.

Supported from the main frame 11 is a primary upright assembly l6 andone or more secondary or movable upright assemblies l7, l8 and 19mounted for vertical movement relative to the primary or fixed uprightassembly 16. The secondary upright assembly 17 is mounted for movementdirectly on the primary upright assembly 16 and the remaining secondaryupright assemblies 18 and 19 are mounted for relative vertical movementin telescoping relationship, as shown in FIG. 3.

A load carriage 20 is mounted for vertical movement on the forwardsecondary upright assembly 19 so that a load can be moved from a lowerposition to the top of the forward secondary upright 19, as shown inFIG. 3. The three secondary or movable upright assemblies can be movedrelative to one another and relative to the primary upright assembly 16.The load carriage 20 includes a pair of horizontal forks 21 adapted toengage and lift a load such as a pallet, as shown in FIG. 2.

As best seen in FIGS. 4 and 5, the primary upright assembly 16 isconstructed of a pair of channel uprights 22 of generally block-Scross-sectional configuration joined together by a vertical plate 23which is welded or otherwise secured to the transverse web 24 of eachupright. It is important to realize that the plate 23 extends through avery substantial part of the length of the channel uprights 22 and actswith those uprights to form an integral unit that has a very high degreeor rigidity. Each of the channel uprights 22 has an outwardly facingchannel 25 and an inwardly facing channel 26. I secure the primaryupright assembly 16 to the truck body by bolts 27 which extend throughthe inwardly facing channel 26.

Each of the secondary or movable upright assemblies is of similarconstruction to the primary upright and each includes a pair of block-Scross-sectional channel uprights 28 having a web 29 with a verticalplate 30 welded to a transverse web 29 to form integral units that havea very high degree of rigidity.

The channel uprights of each of the upright assemblies areinterdigitated as shown in FIGS. 4 and 5. I secure upper rollers 31 tothe rear longitudinal web 32 of each of the uprights which bear againstthe forward face of the transverse webs 24 or 29. A portion of thetransverse flange 33 of each of the uprights adjacent to each of theupper rollers 31 is cut away to enable the rollers to engage thetransverse webs. In like manner, each of the uprights is provided with alower roller 34 rotatably mounted on the front longitudinal web 35 ofeach upright and mounted to engage the rear side of the webs 24 or 29. Aportion of the transverse flange 36 of each of the uprights is cut awayadjacent each of the lower rollers 34 to permit the rollers to engagethe transverse web 24. Thus, all of the upper rollers 31 and all of thelower rollers 34 respectively engage the forward and rear faces of thetransverse webs 24 or 29 of an adjacent upright. Additionally, eachupper roller 31 is surrounded or bounded by the sides of adjacentuprights. Thus, the upper rollers 3| are surrounded by three surfaces orflanges of an adjacent upright as well as to the surface to which it issecured and the lower rollers 34 are likewise so surrounded or nested onall four sides. This novel upright construction provides a mastconstruction of exceptional rigidity. Moreover, I can achieve this rigidconstruction while actually arranging the primary channel uprights 22 inclose relationship to one another with the channel uprights 28 of eachof the movable uprights correspondingly close to one another. Therefore,l am able through my novel inventive concept to contribute an uprightassembly that is very narrow and enables the truck driver to have abetter view from his position on the truck when manipulating a load.

As best seen in FIG. 4, each of the pairs of channel uprights 22 and 28are connected near the bottom end thereof by the plate 38 which iswelded or otherwise secured to the front longitudinal web 35 of each ofthe uprights and extends a slight distance rearwardly thereof beyond thetransverse webs 24 or 29 and the vertical plates 23 or 30 for purposeswhich I will explain hereinafter. At the upper end of each of thechannel uprights 22 and 28, I mount a thrust plate 39 which is welded orotherwise secured to each of the forward webs 35 of the channel uprightswith each of the thrust plates extending rearwardly of the verticalplates 23 or 30 into overlapping relationship with the bottom plate 38of an adjacent upright,

Thus, it will be seen when considering FIGS. 4 and that I can utilizethe space between the channel uprights and each of the vertical plates23 and 30 for a ram cylinder 40 mounted on the bottom plate 38 of theprimary upright with the piston 41 thereof engaging the thrust plate 39of a movable upright assembly 17. In like manner, I mount ram cylinders42, 43 on each of the bottom plates 38 of the movable upright assembliesl8 and 19 as well as a ram 44 for the load carriage 20. Each of the ramcylinders 42, 43 and 44 have a piston 45, 46 and 47 respectivelyconnected to the thrust plate of the next adjacent upright assembly. Thepiston 47 of ram 44 is provided with a sprocket 48 about which a pair ofchains 49 are reeved. The chain ends 50 are fixed to the ram 47 and theother end 51 is connected to the load carriage 20.

The hydraulic circuit for operating the rams includes a reservoir 52,connected by a pipe 54 to a pump 56. The pump 56 is driven by a suitablemotor 58, and is connected to a twoway control valve 60 by a pipe 62.The two-way control valve 60 is connected by a pipe 64 to the bottom endof the first primary ram 40. A pipe 66 is also connected between thetwoway control valve 60 and the reservoir 52.

By this arrangement, fluid is drawn from the reservoir 52 by the pump 56and moved under system pressure to the two-way control valve 60. Fromthe two-way control valve 60, the pressurized fluid can be moved to theram system for lifting purposes. Also, the two-way control valve 60 iseffective to dump fluid from the ram system back into the reservoir 52for purposes of lowering the rams 40 and 42 through 44.

Referring particularly to FIGS. 6 through 8, the bottom end of each ofthe ram cylinders is closed by head member 67 having a threaded axialpassage and a shoulder 69 that supports the cylinder and bears againstthe bottom plate 38. A portion 70 of the head member 67 projects partway into a bore formed in the bottom plate 38 which stabilizes the ramrelatively to the bottom plate. The head member 67, and thus the ram. issecured to the bottom plate 38 by means ofa threaded cap 71 threadedinto the axial passage 68. Suitable sealing means, such as O-rings, areprovided between the bottom plate 38 and the flange of the cap 7], aswell as between the shoulder 69 of the head member and the bottom plate38. The cap 71 is provided with a bore 72 communicating with axialorifices 73, so that when the cap is in assembled position the orifices73 communicate with a passage 74 extending through the bottom plate 38and connected at 75 to a vertical pipe 76.

As seen in FIG. 7 of the drawings, each of the pistons for the rams istubular and extends out through the top of the ram cylinder. The upperend of the ram cylinder is enlarged for receiving a packing seal 77 heldin place by a threaded annular retainer 78. The upper end of the piston4| is threaded to receive a threaded cap 79 having a counterbore 80communicating with orifices 8] which in turn communicates with a passage82 in the thrust plate 39. Suitable sealing means, such as O-rings 83and 84, seal the upper end of the piston to the thrust plate. Thepassage 82 is connected to the vertical pipe 76 which, of course,extends from the thrust plate 39 of one upright assembly to the baseplate of the same upright assembly, as clearly shown in FIG. 8 of thedrawings. It will be understood that the vertical pipe 76 of the primaryor fixed upright assembly communicates with the control valve 60. Also,the ram 44 of the upright assembly 19 is provided with a solid ratherthan a tubular piston provided with the sprockets 48 which operates theload carriage through the lift chains 49.

In summary, the present invention provides a novel upright and ramconstruction in which the uprights are of very rigid and stableconstruction while at the same time being compact to increase theoperator's visibility. Moreover, the upright assembly is actuated byrams which are hydraulically connected in series through a hydrauliccircuit employing a minimum of piping with the further feature that noneof the piping need to be flexible.

Iclaim:

1. A load lifting mast for a truck having an upright and a load carriermounted in front of said upright and having a movable part adapted toimpart lifting movement to said load carrier, the improvement thatcomprises fixing a base plate on the base of said upright with said baseplate having a fluid passage connected at one end to a source of fluidpressure and terminating in an opening, a ram having an opening in itslower end adapted for coaction with the opening of said passage when thelower end of said ram is applied to said base plate, and means securingsaid ram to said base plate and effecting the closing of said openingsto form a continuous sealed passage from said fluid source through saidplate fluid passage to said ram.

2. The invention according to claim 1, wherein said base plate passageterminates at an opening terminating in the upper face of said baseplate and into which the lower end of the ram fits so as to connect theopening of the lower end of the ram with said passage, and meansextending into said base plate and coacting with said ram to secure saidram to said base plate whereby to form said continuous sealed passage.

3. The invention according to claim 2, wherein said means extending intosaid base plate i s a nut entering anopening in the underside of saidbase plate and threaded into the opening of the ram, said ram openinghaving threads formed on its surface for coaction with said nut, saidnut thereby securing the ram to said base plate while closing the openend of said ram.

4. The invention according to claim 3, wherein said nut is itself formedwith an internal opening whereby to establish a flow path from saidfluid passage to said ram.

5. The invention according to claim 1, wherein said upright is a primaryupright and said load carrier is a secondary upright, said secondaryupright having a thrust plate fixed thereto and extending rearwardlyabove said ram and having a passage and an opening formed similarly tosaid passage and opening at said base plate, said ram having a hollowpiston as its movable part with an open end adapted to lift saidsecondary upright through said thrust plate a nd means assembling saidpiston to said thrust plate, aha communicating with the opening andpassage of said thrust plate whereby fluid may flow into said passagefrom said ram.

6. The invention according to claim 5, wherein a base plate assembly onsaid secondary upright like that on said primary upright, and a secondram supported on said base plate and asseml ledtheretoas is the firstram to the primary base plate.

7. The invention according to claim 6 wherein the base plate passage onsaid secondary upright is connected to a fluid passage terminating atthe passage of the thrust plate of the secondary upright.

8. The invention according to claim I. wherein said upright is a primaryupright and said load carrier is a secondary upright, said secondaryupright having a thrust plate fixed thereto, said thrust plate beinglike said base plate on said primary upright but oppositely secured tosaid secondary upright, and means assembling the movable part of saidram to said thrust plate in the same manner as the lower end of the ramis secured to said base plate, said movable part being hollow and havingan opening like the opening in the lower end of said ram.

9. The invention according to claim 5 wherein the base and thrust platesare the same but opposed to one another. and that the open ends of thetwo relatively movable parts of the rams are the same so that the ramsmay be assembled in either of opposed positions between said plates.

